Tank fabricating equipment

ABSTRACT

A design for tank fabricating equipment and system comprises a frame supporting opposing arms for supporting one or more tank shells. The opposing arms pivotally engage opposing sides of the tank shells to force them into a circular cross-sectional shape. The arms are provided with rollers for aligning the tank shell with adjacent components during fabrication. In some embodiments, the rollers are provided with a circumferential channel to accommodate welding seams and to ensure alignment of butt joints.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of U.S.patent application Ser. No. 16/275,922 filed on Feb. 14, 2019, whichclaims the benefit of U.S. Provisional Patent Application Ser. No.62/698,627 filed Jul. 16, 2018, the disclosures of which areincorporated herein by reference.

BACKGROUND Field of the Invention

This disclosure is in the field of equipment used in the fabrication oftanks. More specifically, this disclosure is in the field of equipmentused to align and hold the component parts of a tank during assembly.

SUMMARY OF THE INVENTION

In various embodiments, the tank fabricating equipment comprises atleast one frame supporting a series of extending arms to support andalign a tank shell during tank fabrication. The frames may be mounted onwheels, rails, or other mobile platform to allow them to move inrelation to other frames or other equipment used with the frames.

As the arms extend and contact a partially constructed tank shell, theyconform the tank shell into a desired circular cross-sectional shapeprior to welding. In various embodiments of the equipment, it isprovided with at least one set of arms on each side of the tank shell.The arms are provided with rollers in contact with the tank shell tohold the tank shell in the desired position.

In some embodiments the rollers are specially designed to overlap a seambetween the tank shell and an adjacent tank component, such as anothertank shell or a tank head. In such embodiments, the overlapping rollerresults in improved alignment between the adjacent components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of examples of the types of tanks that maybe fabricated using the tank fabricating equipment.

FIG. 2 is an exploded view of an example of the type of tank that may befabricated using the tank fabricating equipment.

FIG. 3 is a side view of an embodiment of the tank fabricatingequipment.

FIG. 4 is a side view of an embodiment of the tank fabricatingequipment.

FIG. 5 is a side view of an embodiment of the tank fabricatingequipment.

FIG. 6 is a perspective view of a portion of an embodiment of the tankfabricating equipment.

FIG. 7 is a top plan view of an embodiment of the tank fabricatingsystem.

FIG. 8 is a detail view of a portion of an embodiment of the tankfabricating system.

FIG. 9 is a perspective view of the rollers of an embodiment of the tankfabricating system depicting the configuration used to join two segmentsof tank shell.

FIG. 10 is a perspective view of the rollers of an embodiment of thetank fabricating system depicting the configuration used to joinadditional tank components to a tank shell.

FIG. 11 is a detail view of a control panel of an embodiment of the tankfabricating system.

FIG. 12 is a detail view of a portion of the control system of anembodiment of the tank fabricating system.

DETAILED DESCRIPTION

The tank fabricating equipment and system comprises equipment foraligning and holding the component parts of a tank together during thefabrication process so that they can be joined to form the tank.Although this system is capable of use on smaller tanks, it is alsocapable of being used to fabricate large tanks, such as large stainlesssteel tanks used in various types of industrial processing facilities.The tanks typically consist of cylinders, sometimes referred to as tankshells, formed from sheets of stainless steel with two opposing edgeswelded together. After the completion of the tank, the tank shells havesubstantially circular cross-sections. In some cases the tanks have endcaps that are flat circles, conical, or roughly hemispherical in shape,and in other cases one or more ends of the tanks may be open and held inshape by a flange or other structural component. FIG. 1 depicts severalexamples of the finished tanks comprised of multiple tank shells 102 andhead and end pieces 800. A tank as referred to herein need not be sealedon one or either end, but may comprise one or more tank shells that haveflanges on one or both ends for attachment to other components, or evenhave raw edges on either end. Similarly, the resulting output from thetank fabricating and processing equipment may require further processingusing other equipment before it is a completed product.

The tanks are typically constructed of a sheet product such as sheetmetals of various types, including stainless steel. The tank shell istypically formed from sheets of the product that are formed into aroughly cylindrical shape by bringing two opposing edges together, andthen welded or otherwise secured together along those edges. Then twocircular or roughly hemispherical head pieces are attached via weldingor otherwise to the open ends of the cylinder formed by the tank shellto complete the tank body. An example tank is shown in an exploded viewin FIG. 2, with four adjacent tank shells 102 and head and end pieces800.

The tank shell is typically formed, and joined with other tank shellsand components, with the lengthwise axis of the cylindrical tank formedparallel to the surface of the ground. Since the sheet product used toform the tank shell is flexible enough to be formed into a circle, thetank shell often flexes under the force of gravity, or other forces towhich it is subjected, to form an oval cross-section instead of thedesired circular cross-section. This over flexing makes it difficult toalign and attach the head pieces to the tank shell, and can lead toreduced efficiency, increased fabrication times, and lower overallquality of the final product. The tank shells are prone to flexing outof a circular cross-section until the head pieces, flanges, or otherstructural components are attached to the shell to provide it with thenecessary rigidity.

The tank fabrication system described herein provides support to thetank shell during fabrication to maintain it in the desired shape with acircular cross-section. This makes it easier and faster to fabricatetanks with the desired shape and quality of workmanship. The tankfabricating equipment applies forces to one or more tank shells to causethe shell to adopt a circular cross-section. The tank fabricatingequipment also aligns the edges of two adjacent shells while holdingthem in a circular cross-section and rotates them to provide quick,easy, and accurate welding of the seams, both initial manual tackwelding, as well as final computer controlled welding operations.

The tank fabricating system consists of multiple pneumatically orhydraulically actuated roller that are designed to “hug” a tank shelland hold it in the desired cylindrical shape with the circularcross-section while forming a circumferential seam, such as ashell-to-shell circumferential seam or a tank shell-to-headcircumferential seam. The rollers not only support the tank shell frombeneath but also provide support to the shell from above to keep it inthe desired circular shape. Since the wall of the tank may adopt an ovalcross-section due to the force of gravity on the flexible material ofthe tank shell, the rollers contacting the tank shell above thehorizontal center line of the tank shell force the tank shell tomaintain a circular cross-section while the seams are joined, and thehead pieces of the tank are secured in place. The tank fabricatingequipment may be used in the construction of tanks and similar vesselsfrom very small diameter to very large diameter. The rollers may bemounted on the frame using commonly known methods of mounting rollerssuch as bearings or bushings to allow them to rotate with littlefrictional resistance.

The rollers used in this system are designed to overlap two adjacenttank shells and to hold them in the same circular shape and with theiredges adjacent. The rollers then allow the two tank shells to be rotatedsimultaneously and in concert so that an operator may stand in one spotand weld the seam as the tank shells are rotated by the tank fabricatingsystem. This greatly reduces the error in the previously manualalignment process whereby a user would use manual leverage, shims andsimilar tools to force a short portion of the seam into alignment, tackweld it, and then manually rotate the two shells, and repeat the processof manual alignment. This manual process requires a significant amountof time, and can lead to misalignment, and is very physically demandingwork for larger tanks. The tank fabricating equipment described hereincorrects the potential misalignment and removes all manual forcerequired to achieve alignment. It also causes the entire seam to be inalignment at the same time.

Referring now to FIG. 3, a side view of an embodiment of the tankfabricating equipment 100 is depicted with a tank shell 102. The solidline depiction of the tank 102 shows a non-circular cross-section tankshell that is only supported from below by the lower powered rollers401.

In the various embodiments of the system, the arms of the tankfabricating equipment extend above the horizontal centerline of the tankshell section. The shape and outside diameters of any mating shellsections or shells to heads match exactly. As the contact wheels orrollers 404 of the tank fabricating equipment engage the shells 102, thecontact rollers 404 squeeze each separate section inwardly, forcingthose sections to assume and hold their intended shape. Once the rollers404 of the tank fabricating system are brought into contact with thetank shell the force exerted by the rollers 404 forces the tank shell102 into the circular cross-section depicted by the dashed line in FIG.3.

Other “fit up” equipment used in the industry does not include the armsand rollers that contact the tank shell above the horizontal centerlineof the tank shell. “Fit up” is a term used in the tank and vesselindustry and describes the process of joining tank shells to other tankshells, or tank shells to heads. It is necessary that in order for atank to hold its intended contents without leaking, that the heads andshells be securely and completely attached to each other to form anenclosed container.

The traditional method of fit up of shells and heads is to join themtogether in “non-hugging” cradles, moving each set of cradles closetogether and then to begin the labor-intensive process of joining themtogether. The process of causing the adjoining sections to fit end toend is very difficult because the tank fabricator must cause theadjoining sections to line up perfectly. There is a very small margin oferror in the alignment. The tank fabricator must align the adjoiningmaterial thicknesses edge to edge. The adjoining thicknesses may be asthin as 12 gauge (0.105″) thick. The tank fabricator is required by tankand vessel construction code to adjoin the edges within a tolerance of25% of the thickness of the thinner of the two adjoining sections. Inthe case of 12 gauge, that means the alignment must be within0.105″×25%=0.02625″. Manually aligning and checking alignment of largetanks with this very small tolerance for error causes the joiningprocess to be very time and labor intensive.

The tank fabricating equipment described herein eliminates the manualprocess of aligning the edges of the two sections together by using thecontact rollers 404 of the arms to form the tank shell into the desiredshape. By placing the edges of two shells onto the same set of rollers,the force exerted by the rollers automatically aligns the adjacentshells 102. As the arms apply inward pressure on the two adjoiningsections simultaneously it forces the shape and alignment of the tankshells because the adjoining sections are being squeezed with a commonset of contact rollers 404 at a common squeezing force. This processcauses the sections to align perfectly and therefore eliminates themisalignment problems inherent in the traditional method. The 25%alignment tolerance described above is easily met by the tankfabricating system described herein.

Tank fabricators using the tank fabricating system have increasedproductivity dramatically. An example of the labor reduction achieved byusing the tank fabricating system is for an 11′ diameter tank of ⅜″plate thickness. The traditional method of fit up would have takenapproximately 5.5 labor hours for each circumferential fit up. The tankfabricating system completed the same task in only 1.25 hours,comprising a 440% increase in productivity.

Referring now to FIGS. 3-7, various views of an embodiment of the tankfabricating equipment are depicted. The various components of the system100 are supported by a frame formed from a variety of structural members200 formed of steel or other material suitable to support the weight ofthe tank fabricating equipment, the tank shell, and any other equipmentthat may be attached to it. The structure members 200 may be mounted onwheels or rails to allow the entire system and any tank shells thereonto be translated as desired, and may be provided with drive wheels ortracks to move the system.

In this embodiment, three arms 400, 408, and 602 are provided on eachside of the frame. Each arm may be formed from one or more structuralcomponents or arm members that are joined to form arm, which maycomprise a truss structure or other type of structure designed to createa strong arm that is lighter than a single solid member wouldnecessarily be to achieve the same strength. The arms and arm membersmay be considered as two sets, one set disposed on each side of a linedenoting the “center line” of the frame for purposes of tankfabrication, though it need not be the exact center line of the frame.The dashed line shown in FIG. 7 bisecting the top view of the frame isthe logical “center line” of the depicted embodiment. In the depictedembodiment, each set of three arms 400, 408, and 602 are disposed onopposite sides of the center line of the frame, and are oriented so thatthe arms in each set pivot toward the center line of the frame.

Each arm is pivotally attached at a first end thereof to a structuralmember 200 or to a structure attached to the structural members 200,such as structure 414, designed to provide for the upper arms. Each arm400, 408, 602 are provided with actuators 406, 412, and 604,respectively. The actuators are pivotally attached to the structuralmember 200 at a first end of each actuator. The second end of eachactuator is pivotally attached to one of the arms 400, 408, or 602, suchthat operation of the actuator will cause the arm to which it isattached to pivot toward or away from a tank shell disposed on theequipment. As described above, the actuators may be pneumatic,hydraulic, or any other similar actuator capable of exerting thenecessary force.

Roller carriages 402, 410, and 606 are attached to the second end ofeach arm 400, 408, and 602, respectively. The roller carriage ispivotally attached to the second end of each arm. The roller carriagemay have one or more rollers 404 attached to it. In a preferredembodiment, each roller carriage has two rollers attached to it and thecarriage is pivotally attached to the arm at a point on the carriagesubstantially between the two rollers as depicted in the figures. Whenthe arms are pivoted toward the center line of the frame, until therollers come in contact with a tank shell disposed on the equipment, thetank shell is forced into the circular cross-sectional shape by therollers. As can be seen in FIG. 4, at least one roller from each set ofarms contacts the tank shell above a horizontal plane that bisects thecross-section of the tank shell. In some embodiments, such as thatdepicted in the figures, multiple rollers 404 will contact the tankshell above the referenced horizontal plane. The force on the tank shellfrom above this horizontal plane is necessary to force the tank shellinto the desired circular cross-section.

FIG. 5 is a side view of an embodiment of the tank fabricating equipmentbeing used to fabricate multiple tank sizes shown by the solid anddashed lines. As can be seen in this figure, the same embodiment of thetank fabricating system 100 may be used to fabricate various sizes oftanks. As the tank size increases it may become necessary to addadditional arms or to extend the arms with additional actuators androllers. Other configurations for the arm, actuators, and rollers may beutilized as desired within the scope of the invention. In otherembodiments of the tank fabricating system, the number and relationshipof the various arms and rollers may be different then the embodimentdepicted in the figures as necessary to handle varying sizes of tanks.

Referring now to FIG. 6, a partial perspective view of an embodiment ofthe tank fabricating system is depicted. FIG. 6 provides a detaileddepiction of the frame and structure used to support the arms 400 and408, and the actuators 406 and 412 attached thereto. In some embodimentsof the tank fabricating system, specific rollers shown in FIG. 6 areused to provide improved performance of the equipment. In suchembodiments, some or all of the rollers 401 and 404 comprise a singledrum roller 700 supported by a shaft 702 that is preferable a singleshaft. In some embodiments, a circumferential channel 706 is provided inthe outer surface of the cylindrical drum.

In some embodiments, two sections of coating material 704 are providedon the outer surface of the roller 700. In some embodiments the coatingmaterial is urethane or other similar material. In these embodiments thechannel or gap 706 may partially or completely be formed by the gapbetween the coating areas 704 which may expose the drum 700 or consistof a thinner layer of the coating. The drum 700 is a single drum toinsure that the entire surface of the drum 700 is at the same level orcircumference. Similarly the coatings 704 are applied and machined orprocessed to ensure that they are of the same outer circumference.

When these rollers are used on an embodiment of the tank fabricatingsystem, the channels 706 of all the rollers are aligned as seen in FIG.7. When the edges of two tank shells 102 are to be joined together, theyare placed on the rollers with the edges meeting in a butt joint 708above channels 706 of the rollers. The single drum 700 and similarcoating thickness 704 causes the two adjacent shells to be alignedwithin the desired tolerance. The channels 706 allow the weld to passover the rollers without damaging the roller surface or altering thealignment of the two tank shells.

Referring now to FIG. 8, a detailed perspective view of a portion of anembodiment of the tank fabricating equipment is depicted. In thisembodiment, the two opposing sets of rollers and arms may be movedcloser together or farther apart as necessary to accommodate varyingsizes of tank shells. The frames 416 to which the rollers and arms areattached may be translated on structural members 200. The frames 416 areprovided with a hole 712 for receiving a pin 710. At various desireddistances, holes 714 are provided in structural member 200. By aligningholes 712 and 714, and inserting pin 710 therein, the relativedimensions of the two frames may be adjusted as desired.

Referring now to FIGS. 9 and 10, embodiments of the tank fabricatingequipment are shown to illustrate the process of joining two or moretank shells together. In FIG. 9, the tank fabricating system 100 isshown with two tank shells 102 disposed thereon. The two shells 102 meetat butt joint 708 which is aligned with the gaps 706 in coating areas704. The two shells are supported by contact with the coating areas 704so that a gap is provided between the outer surface of the drum 700 andthe tank shells 102 in gap 706.

The arms (not shown in FIGS. 9 and 10) are pivoted toward the tankshells 102 until rollers 404 contact the outer surface of the tankshells 102 on either side of the butt joint 708. The actuators increasethe force on the arms until the rollers apply sufficient force to thetank shells to conform them to the desired circular cross-section. Aseparate lateral force may be applied to the tank shells 102 that isperpendicular to the butt joint 708 to cause the joint to be forcedtogether. In some cases, this lateral force is applied by using a“come-along” or similar device to pull the outer edges of each tankshell 102 toward the butt joint 708 thus pushing the butt jointtogether.

Once the tank shells 102 are aligned and pulled tightly together, thedrive rollers 401 may be rotated using a motor in a first direction tocause both of the tank shells to simultaneously rotate in the oppositedirection. The rotation may be continuous or periodic as desired by theoperator of the equipment. As the tank shells rotate, a welder may standon the outside of the equipment between the arms and tack weld the buttjoint 708 with or without stopping the rotation of the tank shells 102.

Once the butt joint 708 is tack welded, a finish welder may be insertedover one of the tank shells to position a welding head at the butt joint708, for example in the area of the butt joint above and between thehighest rollers 404. In some embodiments of the system, the finishwelder head is computer controlled, and the drive rollers are undersimultaneous computer control by the same system so that the weldingsystem operates to rotate the shells 102 past the finish welding headduring the final weld operation.

Referring now to FIG. 10, additional pieces of tank fabricatingequipment may be used together to support tank shells 102 as morecomponents are added to the tank. These additional components may beadditional tank shells 102 that are joined at butt joint 716, or caps orflange 718. When the component is a flange or similar component thejoint 718 may be formed to the side of the tank fabricating equipment100 with the edge of the tank shell 102 that is to be joined to theflange extending out to the side. The flange or other component may beclamped onto the shell and then the drive rollers used to rotate thecombination for welding as described above.

FIG. 11 is a view of a control panel of an embodiment of the tankfabricating system. The control panel provides an operator with thecontrols necessary to operate the various components of the system, andincludes emergency stop and other safety features. It may providecontrols to cause the drive rollers 401 to rotate in one or moredirection, as well as controls to cause the arms to pivot toward or awayfrom the tank shells 102. The control unit may also provide controls forthe speed of arm or roller movement, as well as gauges or other displaysshowing the settings and status of the equipment. Some embodiments mayalso provide controls to translate the equipment on rails or by othermeans. A single control unit may provide controls for multiple units ofthe tank fabricating equipment.

FIG. 12 is a detail view of a portion of the control system of anembodiment of the tank fabricating system. This embodiment is a handhelddevice for controlling the equipment and its various functions.Actuators may be provided for controlling each set of arms individuallyor simultaneously. Drive roller actuators may also be provided, inaddition to an emergency stop actuator.

“Substantially” means to be more-or-less conforming to the particulardimension, range, shape, concept, or other aspect modified by the term,such that a feature or component need not conform exactly. For example,a “substantially cylindrical” object means that the object resembles acylinder but may have one or more deviations from a true cylinder.

“Comprising,” “including,” and “having” (and conjugations thereof) areused interchangeably to mean including but not necessarily limited to,and are open-ended terms not intended to exclude additional, unrecitedelements or method steps.

In other embodiments of the equipment and system, computer control via ageneral purpose or specific purpose computer may be utilized. In suchembodiments, a user interface may be provided for a user to inputcontrols or program the operation of the equipment. In such embodiments,the computer control system may simultaneously control other relatedequipment such as welding systems to coordinate the operation of thevarious pieces of equipment. For example, a computer welding controlsystem may also control the rotation of the drive rollers 401 toautomate the final welding of a butt joint between two tank shells. Thedetails of implementing a control system for the disclosed system willbe apparent to one of skill in the art of controlling pneumatic orhydraulic systems, or for providing computer control of such systems.

Many different arrangements of the various components depicted, as wellas components not shown, are possible without departing from the spiritand scope of the present invention. Embodiments of the present inventionhave been described with the intent to be illustrative rather thanrestrictive. Alternative embodiments will become apparent to thoseskilled in the art that do not depart from its scope. A skilled artisanmay develop alternative means of implementing the aforementionedimprovements without departing from the scope of the present invention.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations and are contemplated within the scope of the claims. Notall steps listed in the various figures need be carried out in thespecific order described.

The invention claimed is:
 1. A tank fabrication machine for joining atleast two tank components, at least one of which is a tank shell; thetank fabrication machine comprising: a frame composed of at least onestructural member on each side of a center line of the frame; a driveroller mounted on the frame; a first arm member and a second arm memberattached to the frame on opposing sides of the center line of the frame;a third arm member and a fourth arm member attached to the frame onopposing sides of the center line of the frame; a first arm rollermounted on said first arm member, a second arm roller mounted on saidsecond arm member, a third arm roller mounted on said third arm member,and a fourth arm roller mounted on said fourth arm member; a tank shelldisposed on the drive roller; wherein a first end of each of said first,second, third, and fourth arm members is pivotally mounted onto theframe; wherein said first arm member is configured to bring the firstarm roller in contact with the tank shell above a horizontal plane thatbisects the tank shell and said second arm member is configured to bringthe second arm roller in contact with the tank shell above thehorizontal plane that bisects the tank shell; and wherein said third armmember is configured to bring the third arm roller in contact with thetank shell below the horizontal plane that bisects the tank shell andsaid fourth arm member is configured to bring the fourth arm roller incontact with the tank shell below the horizontal plane that bisects thetank shell.
 2. The tank fabrication machine of claim 1 wherein the firstand second arm members are configured to apply pressure to the tankshell sufficient to conform the tank shell to a circular cross-sectionalshape.
 3. The tank fabrication machine of claim 2 wherein each of saidfirst, second, third, and fourth arm rollers further comprises acircumferential channel formed in a surface of each of said first,second, third, and fourth arm rollers.
 4. The tank fabrication machineof claim 3 having a first coating spaced apart from a second coating onan outer surface of each of the first, second, third, and fourth armrollers, wherein each circumferential channel is formed by a gap betweeneach first coating and each second coating, respectively.
 5. The tankfabrication machine of claim 4 wherein each first coating and eachsecond coating are machined to a common circumference.
 6. The tankfabrication machine of claim 4 wherein all of the first arm roller,second arm roller, third arm roller, and fourth arm rollercircumferential channels are aligned.
 7. The tank fabrication machine ofclaim 6 wherein the first arm roller is attached to a first rollercarriage, and the first roller carriage is pivotally attached to thefirst arm member; the second arm roller is attached to a second rollercarriage, and the second roller carriage is pivotally attached to thesecond arm member; the third arm roller is attached to a third rollercarriage, and the third roller carriage is pivotally attached to thethird arm member; and the fourth arm roller is attached to a fourthroller carriage, and the fourth roller carriage is pivotally attached tothe fourth arm member.
 8. The tank fabrication machine of claim 1further comprising a fifth arm member having a fifth arm roller, and asixth arm member having a sixth arm roller; wherein the fifth arm memberand sixth arm member are each pivotally attached to the frame andconfigured to bring the fifth arm roller and the sixth arm roller,respectively, in contact with the tank shell.
 9. The tank fabricationmachine of claim 8 wherein the fifth and sixth arm members areconfigured to apply pressure to the tank shell to conform the tank shellto a circular cross-sectional shape.
 10. The tank fabrication machine ofclaim 2 wherein activation of the drive roller causes the tank shell torotate while maintaining a substantially circular cross-section.
 11. Atank fabrication machine for joining a first tank component to a secondtank component, the tank fabrication machine comprising: a first upperroller and a second upper roller; a first lower roller and a secondlower roller; wherein the first and second lower rollers are configuredto support the first and second tank components from below a horizontalplane that bisects the tank components; wherein the first and secondupper rollers are configured to apply pressure to the first and secondtank components from above the horizontal plane that bisects the tankcomponents wherein each of said first upper, second upper, first lower,and second lower rollers has a first coating spaced apart from a secondcoating on an outer surface such that a circumferential channel isformed by a gap between the first coating and the second coating,wherein all of the first upper roller, second upper roller, first lowerroller, and second lower roller circumferential channels are aligned.12. The tank fabrication machine of claim 11 wherein the first andsecond upper rollers apply sufficient pressure to conform the tankcomponents to a substantially cylindrical cross-sectional shape.
 13. Thetank fabrication machine of claim 12 wherein one of the lower rollers isa drive roller configured to rotate the tank components.
 14. The tankfabrication machine of claim 13 wherein the first upper roller isdisposed on an opposite side of a vertical plane that bisects the tankcomponents from the second upper roller.